Dressed black holes in the new tensor-vector-scalar theory

TL;DR

This paper explores black hole solutions within a tensor-vector-scalar modified gravity theory, revealing mostly Schwarzschild-like solutions but with potential divergences at the horizon, raising questions about their physical viability.

Contribution

It introduces black hole solutions in a tensor-vector-scalar framework of modified gravity, highlighting their similarities to Schwarzschild black holes and discussing horizon divergences.

Findings

Black holes in the theory are mostly Schwarzschild-like.

Scalar and vector fields diverge at the event horizon.

Divergences may be resolved if black hole hair vanishes.

Abstract

As incarnations of gravity in its prime, black holes are arguably the best target for us to demystify gravity. Keeping in mind the prominent role black holes play in gravitational wave astronomy, it becomes a must for a theory to possess black hole solutions with only measurable departures from their general relativity counterparts. In this paper, we present black holes in a tensor-vector-scalar representation of relativistic modified Newtonian dynamics. We find that the theory allows Schwarzschild and nearly-Schwarzschild black holes as solutions, while the nontrivial scalar and vector fields generally diverge at the event horizon. Whether this is a physical pathology or not poses a challenge for these solutions, and by extension, the model. However, even if it is, this pathology could be overcome when the black hole hair vanishes.